Graph Evolution via Social Diffusion Processes - VideoLectures

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Graph Evolution via Social Diffusion Processes Dijun Luo Chris Ding Heng Huang University of Texas at Arlington

Outline • Introduction

• Motivation • Social Diffusion Processes • Applications • Experimental Results • Conclusions

Introduction • Graph-based clustering approaches are widely employed • Simple, easily to understand, good results [Shi-Malik1997, Ng et al

2001, Chan et al 1993] • Graph data are widely available • Most of previous research focus on static analysis of graph • Graph partition seeks grouping using static optimization, cut edges between clusters • Stochastic modeling maximize the likelihood of a generative model on the graph. • Our work present a novel dynamic analysis of graph data • Inspired by Matthew effect, a general phenomenon in nature and

societies • Stronger connections become stronger • Expand and smooth social circles

Motivation • The relationship among people in a society changes in time • People are typically involved in many social events • E.g. meeting new friends, attending conferences like ECML here • The more we meet with each other in a conference, the more familiar we are

• People will connect with each other using the connection, like meeting

friends’ friends • Several observations • Two people with many common friends have a lot of chance to know each other • Two good friends have good chances to meet in the same social events, hence they know each more • Social Diffusion Process • An analogue of the social relationship evolution

Motivation case study: Facebook

Motivation case study: Facebook We will see the events of our friend’s friends

Motivation case study: Facebook

More common friends means more chance to know the event

Social Diffusion Process • Two friends set up a date. They meet. • Two friends set up a date. One brings along a friend. The

three of them meet. • Two friends set up a date. Both friends bring along a

friend each. The four of them meet. There exist more processes. But these are the most fundamental processes. We consider them only in this work.

Social Diffusion Process • Two friends set up a date. They meet. • Two friends (A,B) set up a date. One (B) brings along a

friend (C). The three of them meet. • A meets C

• Two friends (A,B) set up a date. Both friends bring along a

friend [A brings C. B brings D]. The four of them meet. • A meets D • B meets C;

• Most importantly, C meets D

• Diffusion: two person meet due to their friends’ initiative

Social Diffusion Process • Two friends set up a date. They meet.

• Two friends (A,B) set up a date. One (B) brings along a friend (C).

The three of them meet. • A meets C (two person meet due to a common friend)

A

C B

• Two friends (A,B) set up a date. Both friends bring along a friend

[ A brings C. B brings D ]. The four of them meet. • A meets D (two person meet due to a common friend) • B meets C (two person meet due to a common friend)

• Most importantly, C meets D (two person meet due to a friend’s friend)

C

D

A

B

Social Diffusion Process •

Two friends setup date. They meet Two friends setup date. One brings along a friend. They meet. Two friends setup date. Both bring along a friend. They meet.

Social Diffusion Process • Assume we want to date with some one on the wedding

of Royal wedding for William and Kate, who are we going to date? • We will bring important friends

• Observations • We will choose different level of friends to attend a different events

• The bring-friend action should have a threshold

Social Diffusion Process •

Social Diffusion Process • Uniform distribution

Diffusion constant Set to 1 in algorithm

Social Diffusion Process Model Define thresholded graph adjacency matrix as Proportional constant Set to 1 in algorithm

random walk probability : Pk i

Akit  dk

Social Diffusion Process

Diffusion constant Set to 1 in algorithm

random walk probability : Pk i

Akit  dk

Social Diffusion Process Algorithm

The only model parameter

Social Diffusion Process: a simple case

Social Diffusion Process: a simple case

Social Diffusion Process: a simple case

Applications • Clustering • Grouping results can be derived when disconnected components are observed • Preprocessing for other machine learning tasks • Our algorithm take a graph as input and a better graph as output • Can be used as preprocessing • Clustering, semi-supervised learning etc.

Experimental Results • Empirically show that our algorithm converges

• Clustering • Semi-supervised learning • MicroRNA data analysis

Experimental Results Convergence analysis

Experimental Results: Clustering

24 UCI Data Sets

Experimental Results: Semi-supervised Learning

Experimental Results: microRNA function analysis

Experimental Results: microRNA function analysis let-7 microRNA family

Experimental Results: microRNA function analysis

rna-200 microRNA family

Experimental Results: microRNA function analysis • The corresponding genes

Experimental Results: microRNA function analysis • Observations • 6 microRNA groups are identified • let-7 and mir-200 family a have been reported by other researchers [Hu 2009, Abbott 2005]

Conclusions • A novel social diffusion process model is presented • Dynamic graph evolution • Analogue of the Mathew effect • Simple, intuitive, interpretable • Directly corresponds to graph language

• Extensive experiments on 24 UCI data sets • Better clustering accuracy • Better semi-supervised learning performance • Unsupervised graph-data exploration • Almost no parameter • Easy to visualize • Meaningful results